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A Selection of micro:bit Projects

Getting Started Getting started with the micro:bit should be plain sailing. There are lots of excellent instructions,

videos and tutorials available to help you get going with your BBC micro:bit at the official micro:bit

web site (http://microbit.org/start/).

If you’ve never used a BBC micro:bit before, then it’s worth taking some time to explore this web

site before you get going on the projects that we’ve put together for you. However, if you’re already

familiar with the micro:bit and how to use it then feel free to move on to the projects described

below.

Introduction The projects described in this document are designed to show you the sorts of things that can be

done with the BBC micro:bit. A lot of these projects involve connecting the micro:bit to other bits

and pieces; such as buzzers, or LEDs. However, we start off with a really simple project which just

uses the micro:bit on its own.

micro:bit Dice Our micro:bit dice project uses the onboard LED matrix and accelerometer to simulate a die. Simply

shake the micro:bit, and it will generate a random dice throw, and display it on the micro:bit LED

matrix. To create the code for this project, head over to the micro:bit web site, and select the ‘Let’s

Code’ link (http://microbit.org/code/). From this page you’ll need to create a new project using the

JavaScript Blocks Editor. If you’ve not used the micro:bit Blocks editor before, there are tutorials

available at the BBC micro:bit web site to help you on your way.

When you create your new project, you’ll be presented with a blank canvas on which to create your

program. Select the blocks you want to use by dragging them into place on the canvas.

For the micro:bit dice project, the first block that you will need is the ‘on shake’ block, which can be

found under the ‘Input’ tab. So, click on the ‘Input’ tab, and drag the ‘on shake’ block on to the

canvas.

The next block you’ll need is the ‘set’ block, to allow us to set up a variable called ‘roll’. This block is

under the ‘Variables’ tab; so click on ‘Variables’ and drag a ‘set’ block into place within the ‘on shake’

block.

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You’re going to use a variable called ‘roll’, so to rename your variable (currently called ‘item’), click

on the word ‘item’ and select ‘Rename variable…’ from the menu that appears. In the prompt that

appears, enter the text ‘roll’, and press OK to rename the variable.

Next, you will need to set the value of the variable ‘roll’ to have a random value. For this, you’ll need

to select the ‘Math’ tab, and drag a ‘pick random’ block into place next to the ‘set’ block.

For a dice roll, the random number chosen should be between 0 and 6, so you will need to change

the number in the ‘pick random’ block to have a value of 6 instead of 4.

Having picked the random number, you will then need to display the number somehow. For this you

will use the 5×5 LED matrix. However, the pattern displayed by the LEDs will depend on the value of

the variable ‘roll’, so it will be necessary to introduce an ‘if’ block into our program. To do this, select

the ‘Logic’ tab, and drag an ‘if’ block into place within the program as shown in the diagram below.

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The ‘if’ statement will need to check the value of the variable ‘roll’, so the next step will be to drag a

code block that will let you compare 2 numbers. This comparison (‘=’ or equality) code block is under

the ‘Logic’ tab. Drag this ‘=’ code block into place as shown below.

Having done this, you will need to replace the ‘0’ blocks with the correct values. You need to check

to see whether the value of the variable ‘roll’ is equal to a number (for example 6), so replace the

first ‘0’ with the variable ‘roll’ (you will find this under the ‘Variables’ tab), and replace the second ‘0’

with the number ‘6’; as below.

Next you need to define the LED pattern that will be displayed for a roll value of 6. LED patterns are

set up using the ‘show LEDs’ block under the ‘Basic’ tab, so drag one of these blocks into place next

to the word ‘then’ in the ‘if’ block.

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Then draw the pattern for a dice throw of 6 by selecting which of the LEDs should be lit up for this

dice throw.

As it stands, the dice will only indicate a throw of 6, so the next step is to check for other values of

the variable ‘roll’. This is done by means of ‘else if’ and ‘else’ statements. To create these

statements, you will need to click on the settings icon in the ‘if’ block, then drag a number of ‘else if’

and ‘else’ blocks into place within the ‘if’ block. You will need to create 4 ‘else if’ blocks and a single

‘else’ block, as below.

Having done this, click on the settings icon again, and the ‘if’ block settings will disappear, leaving

you with the gaps required for dragging other ‘=’ and ‘show LEDs’ blocks into place.

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Finally, drag in the comparison (‘=’) blocks and ‘show LEDs’ blocks for the various other possible

values of the variable ‘roll’. You only actually need to check 4 other values (5, 4, 3 and 2), as if it is

none of these values, then it must have a value of 1 or 0 (you’ve already checked for the value of 6).

For our dice, if the random roll has a value of 0 we’re going to display it as if it were a 1, as we have

no way of displaying a 0; although theoretically, this does mean that your dice will have a slightly

higher chance of rolling a 1.

The diagram below shows what your completed code for the micro:bit dice (or die) should look like.

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Dice Blocks

Having completed the code for the micro:bit dice, you can try running it in the on-screen emulator

by clicking on ‘SHAKE’ on the micro:bit on the web page. This will allow you to check out your code

before downloading it to your micro:bit.

Once you’re happy that the code is working correctly, try downloading it to your micro:bit. To do

this, you’ll need to ensure that your micro:bit is connected to your PC using the USB cable. The

micro:bit should show up as a USB drive called ‘MICROBIT’. Having done this, click on the ‘Download’

link on the web page to generate the program code which needs to be downloaded to the micro:bit.

Depending on which browser you are using you may have the option to save the generated file (it

should have a file extension of ‘.hex’) straight to the micro:bit. If your browser does not support this,

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then you’ll need to open the folder in which the .hex file was generated, and then copy the file to

the micro:bit drive.

Once the .hex file has been copied to the micro:bit it should start running; so try shaking your

micro:bit, and see what happens. If the program runs as expected, you can try disconnecting the

micro:bit from the USB cable, and connect a separate battery power supply to power your micro:bit

die.

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micro:bit Buzzer Our next project gets you started with connecting some simple electronic components to your

micro:bit. The first electronic component we’re going to try out is our buzzer. For this project you’ll

need the micro:bit (and its USB cable or course), a buzzer, and 2 crocodile clip leads. It doesn’t

matter what colour leads you use, and it doesn’t matter which terminals on the buzzer they are

connected to. Connect one of the leads from the micro:bit terminal marked ‘GND’ (ground) to one of

the terminals on the buzzer. Connect the second lead from the micro:bit terminal marked ‘0’ to the

other terminal on the buzzer.

You should have a circuit looking something like the diagram below.

Buzzer Circuit

To check that your buzzer circuit works, you will need to create the following code in the micro:bit

block editor, and download it to the micro:bit. This time, you won’t be able to check the program

out first using the on-screen emulator, but hopefully this shouldn’t be necessary anyway, as the

program is a fairly simple one. So, having created the code, download it to your micro:bit and try it

out. Hopefully when you press the ‘A’ button on the micro:bit, you should hear a two tone buzz from

your buzzer.

Buzzer Blocks

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micro:bit Theremin If you’ve got your buzzer working successfully, why not take things a stage further and have a little

fun with it by making a simple and fun musical instrument. The instrument you’re going to have a go

at creating is something called a Theremin, and it doesn’t require any modifications to the buzzer

circuit that you’ve just created. If you’ve not come across the Theremin before, have a look at the

following link which explains a little about what it is and how it works:-

https://en.wikipedia.org/wiki/Theremin

The code for the micro:bit Theremin was originally written by David Whale, but we’ve adapted it

slightly to allow breaks (rests) in the music created by this somewhat bizarre musical instrument. In

our modified version of the Theremin, the buzzer will only play a sound while the ‘A’ button is being

pressed. Our modified Theremin code is shown below. Try creating this code and downloading it to

your micro:bit (you may need to hunt around a little to find the blocks that you need, but they

shouldn’t be too difficult to find). Having done this, if you move the micro:bit around while pressing

the ‘A’ button, it should play a bit of a tune.

Theremin Blocks

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micro:bit Miniature Steady Hand Game Our next little project still uses the buzzer circuit that you’ve previously used, but now requires you

to connect a little more circuitry. You’re going to have a go at creating a micro:bit miniature steady

hand game, for which you’ll need the buzzer circuit together with 2 more crocodile clip leads, a

breadboard and a couple of paper clips. The paper clips will be used to create your steady hand

game course and a wand to use with it; and you’ll need to bend these into shape to create the

course and wand that you want for your version of the game. The breadboard is used as a stand to

hold the game course paper clip. Both the course and the wand will need to be connected to

terminals on the micro:bit using the 2 crocodile clip leads, as shown in the circuit diagram below.

Steady Hand Game Circuit

The following pictures show our setup.

Steady Hand Game

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Steady Hand Game Track and Wand

The code for this game is fairly straightforward, as all it needs to do is to get the buzzer to make a

sound, and display a cross on the micro:bit’s LED matrix when the wand comes into contact with the

game track. The code blocks to do this are shown below.

Steady Hand Game Blocks

You could try creating a larger version of the game using an old wire coat hanger and a lump of

plasticine as a stand for the course.

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micro:bit Fruit Keyboard Our next project also uses the buzzer circuit. In addition, you’ll need the remaining crocodile clip

wires, and a couple of pieces of fruit or vegetable, which need to be connected up as shown in the

diagram below.

To make this project work, you need to be in contact with the wire that is connected to the ‘GND’

(ground) connector on the micro:bit. You can do this by simply touching the metal end of the

crocodile clip. When you touch one of the pieces of fruit or vegetable, the micro:bit is able to detect

this, and will play a tone through the buzzer. You don’t have to use fruit or vegetable, as this will also

work with things like jelly babies, wiggly worm sweets, or anything else which will conduct very small

amounts of electric current which the micro:bit is able to detect.

Fruit Keyboard Circuit

The code block for our fruit keyboard is shown below. Although it’s unlikely you’ll be able to play

much of a tune with just 2 notes, you could try experimenting with using different notes.

Fruit Keyboard Blocks

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micro:bit Traffic Lights For our final project, we’re going to make a simple set of traffic lights. This project makes use of the

micro:bit, breadboard, 4 crocodile clip wires, and 3 LEDs.

Before putting the circuit together, it’s worth taking a quick look at the LED. If you examine one of

the LEDs closely, you should notice that one of the leads is slightly longer than the other. This longer

lead is generally referred to as the anode, which is the positive terminal of the LED. The other lead is

the cathode, or negative terminal. The LED will only light up if it is connected the correct way round.

You can try this out by simply connecting the LED to your micro:bit as shown below, using 2 of the

crocodile clip leads. The micro:bit will need to be connected to your PC or powered using the battery

pack. Provided that the LED is connected the correct way round, it should light up.

micro:bit and LED

For our traffic light circuit, you’ll need to push the pins of the 3 LEDs into your breadboard, being

careful to ensure that the shorter pins of each of the LEDs (the cathodes) are all in line down one of

the strips on one side of the breadboard (as shown in the circuit diagram below). The anodes must

all be in different breadboard strips. One of the cathode (short) LED pins needs to be connected to

the ‘GND’ (ground) connector of the micro:bit, using one of the crocodile clip wires. Because the LED

pins are all in the same strip of the breadboard, this means that they are effectively connected

together. This arrangement is generally referred to as a ‘common cathode’ connection. The longer

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pins (the anodes) of the 3 LEDs should be connected to connectors ‘0’, ‘1’, and ‘2’ using the other 3

crocodile clip leads. You’ll need to be careful that the ends of the crocodile clips on the LEDs do not

come into contact with each other.

Traffic Lights Circuit

The image below shows our completed micro:bit traffic lights circuit.

Traffic Lights

To make the traffic lights work, you’ll need to create the following arrangement of code blocks, and

download the code to your micro:bit in the same way as you’ve done for your previous projects.

After you download the code to the micro:bit, the green LED should light up. When you press the ‘A’

button, the traffic lights should change through a normal sequence, ending up with the green LED

on.

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Traffic Lights Blocks